Cracking open the Osborne 1: The original portable computer

A classic luggable PC

The Osborne 1 was the word's first self-contained portable personal computer. Many of the design decisions and innovations first seen in the Osborne 1 are still being used today some 25-plus years later. We could not resist taking a look inside this piece of computing history in this TechRepublic Cracking Open Photo Gallery.

A quick note on the Cracking Open Photo Galleries: I am not an engineer and these galleries are not attempts to name every chip we see. So please, if you have knowledge about what is inside the Osborne 1, share it with us.

Keyboard

Remove a couple of screws at the underside of the keyboard is revealed.

Mechanical

The keyboard is a throwback to the era of typewriters.

Ribbon cable

Here we seen the common ribbon cable connecting the keyboard to the rest of the machine. I wonder if this was innovative or imitative? When were ribbon cables first used in these sorts of devices?

Spring

A better look

The familiar latch

The keyboard connects to the Osborne 1 using a ribbon cable and latch system.

Open the latch

Easily removed

The keyboard can be easily removed and then reattached.

Plastic

Our Osborne 1 has seen some time in a basement, attic, or some other place were the plastic could lose some of its strength. Notice that some of the screw holes have deprecated to the point where they don't actually hold the cover to the case anymore.

Nothing last forever

From this angle you can see where the some of the screw holes have disintegrated.

Getting inside

Apparently our Osborne 1 has been cracked open before -- there are several screws missing and later on I discover screws that just don't belong.

Warning

One thing I did notice as I worked my way through the case is that there a numerous warnings. Is opening a PC really all that dangerous?

Mostly floppy drive

With the case removed the most dominate parts seem to be the floppy drives.

A cathode ray tube

Our first look at the cathode ray tube for our display. This is by far the heaviest part in the Osborne 1.

Backside

Those ribbon cables connecting the two floppy drives to the controller look very familiar.

Power

The power assemblage looks impressive, we'll have to get a closer look.

Motherboard

The main circuit board is attached with three screws. Two look to be the original screws one is a flat-head replacement and one is just plain missing.

More to come

The remaining circuit board is associated with the power system. I have no idea what those scratches on the plastic frame is all about.

Chips ahoy!

Our Osborne 1 doesn't skimp when it comes to the overall number of chips.

Previous incursion explained

Apparently our Osborne 1 was upgraded with the double density floppy disk drive controller daughter board. I cannot explain why several screws went missing during that upgrade or subsequent maintenance.

The other end

The CPU can be found on this end of the board. The Osborne 1 used the Zilog Z80 processor running at 4MHz. Or at least a processor based on the Z80.

Memory banks

64K RAM takes up more room then you might think in 1981.

Hello Moto

These memory chips were provided by Motorola.

Except for that chip in the upper left corner. Perhaps this Osborne 1 was opened more than once.

International

Even in 1981, PC making was an international effort. You can see stamps from the Philippines, El Salvador, and Brazil.

Call to experts

Okay all you engineers out there -- what are the two chips from the Philippines for?

NEC

This Osborne 1 has the NEC version of the Z80 processor.

Fujitsu

The large chip above the unknown one from the Philippines is from Fujitsu. According to the chip's data sheet it is a Floppy Disk Formatter / Controller. That makes sense because of the floppy disk connection right next to the chip.

ROM

Which ROM is this?

Printer connection

Name plate

Details

Here are some more details about the origin of our Osborne 1.

You are my density

A close up look at the double-density controller board.

Power regulation

There certainly are a lot of capacitors.

Danger!

I guess it is dangerous - I was careful.

No leaks

Over 25 years old and no leaks -- take that Dell.

Fuse

The Osborne 1 uses an old fashioned fuse. I wonder if this had to be replaced before?

More warnings

The folks at Osborne really wanted to keep people away from this circuit board.

CRT

A close up look at the CRT. And more warnings about electricity.

CRT

CRT

More international flavor

The CRT, at least in part, seems to be from our friends at the Nippon Electric Company in Japan.

3M

Get the parts where you get the parts.

CRT

CRT

Floppy disk drive

The floppy drives are called full-sized but this is ridiculous. This drive is almost the size of a modern notebook computer.

Belt driven

The drive mechanism is belt driven -- seems to be asking for failure.

Floppy chips

It took quite a bit of computing power to read and write files to a floppy disk in 1981, if the number of chips involved can be used as a measure.

Texas Instruments

Looks like Motorola and Texas Instruments were the prominent players for this chip set.

Look at all that space

No wonder later iterations of the floppy drive were cut in half -- most of this drive is wasted empty space.

Another country

More international evidence -- Malaysia is represented.

Floppy drive

Engineer help needed

Okay, I need some help here. Is that part with the "wings" a heat sink?

Floppy drive

All the parts

The end

There were a surprisingly large number of parts in the Osborne 1. I will be interesting to see if the TRS-80 Model 4P has as many.

Floppy drive

About Mark Kaelin

Mark Kaelin is a CBS Interactive Senior Editor for TechRepublic. He is the host for the Microsoft Windows and Office blog, the Google in the Enterprise blog, the Five Apps blog and the Big Data Analytics blog.

Full Bio

Mark Kaelin is a CBS Interactive Senior Editor for TechRepublic. He is the host for the Microsoft Windows and Office blog, the Google in the Enterprise blog, the Five Apps blog and the Big Data Analytics blog.

I used to carry one of those "portable" computers from my office to meetings. Going through an Airport, especially if you had a close connection was a real challenge. Thank goodness there was no TSA back then or that thing would have never made it through security. It was as big as a small suitcase and weighed in at around 30 lbs. It was a real dog to put in the overhead compartments. You had to have a power connection, as there was no batteries. It only ran DOS with no graphics or color screen. Even though there were all of those drawbacks, it was the best way for me to manage my business projects. It sure beat having to working on my Commodore 64.

I worked at a company where the east coast division had Osbournes, and the west coast division had IBM's.
The Osbournes were a LOT lighter when we hauled them along on an airplane.
Use it in-flight? NOT!
Thanks for the memories, Mark.

I loved my OsbornI so much that I bought a second one! I also bought the later Osborn Executive, what a nice machine the Executive was. It was 1/3 the weight, 10 or 12" screen and high density floppy's. I surly hated to move on to the real world of PC DOS a few years later but time moved on.
Our Osborn club, yes we had a real club with upwards of 500 members! The "First Rochester Osborne Group" or F.R.O.G. (of which I'm a past president) was a place of great learning as well as joint computer exploration. Now were the Rochester Computer Society.

The two chips from the Phillipines? 6821 PIA's (Peripheral Interface Adapters). These might be connected to parallel ports, such as for the printer, or possibly to another device on the board. It basically provides an electronically buffered point of connection to a particular set of addresses in the memory or I/O space.

Wow. When I saw your close-up of the ROM BIOS chip, I fumbled around on my desk at work to find the ROM BIOS chip that I had laying around as a novelty item for years. The label was character-for-character identical to the one in your picture, which surprised the heck out of me.
Mine came out of a blue/gray case O1 when I replaced it with a new, official OCC upgrade ROM BIOS chip. I also had the technical manual (a thick 3-ring binder) that someone else mentioned. In addition to the schematics and lots of other cool info, it included a complete *commented* source code listing of the ROM BIOS. (IIRC, the technical manual cost me about $50 new from OCC.)

5pts

I had one of these and remember it well. Booting CPM from a floppy disk, bundled applications like WordPro and SuperCalc, and that tiny screen!
It was a great first computer; Though I am grateful for Moores Law!
Start a New Life, Not a New Job!? at http://Ex-Employee.com

My favorite was a HP Portable, and then the Portable+. It was light (almost even by modern standards), ALWAYS on (CMOS logic), did not crash and was all but bullet proof physically (drop tested to 3 feet. pick it up and keep on typing). It was a true laptop, when most "portables" were indeed "lugables." I can't find a modern laptop/operating system that meet those standards: now we have better GUI, more memory for bloat-ware yes... always on reliable, not any more.

A beautiful piece for it's time and it ran on the CPM operating system, which, in my view was a better dos than IBM(MS) dos. I seem to recall that IBM were late for a meeting with a couple who "invented" CPM and so they scheduled a meeting with a bunch of dropouts who dazzled them with crap and we are still paying the price... long live Dos, unix, linux, pick and everything else not MS.....

The Osborne 1 was not the first portable computer. I worked for Computer Devices in 1980 and I believe we had the first portable computer. It had a built-in thermal printer, either a phone coupler for 110 baud (boy that was fast) or an RJ-11C direct connect for 1200 baud (blow your sock off). It had 32k of RAM and 32k of ROM for the memory and used digital version of a transcription tape for offline storage. It was powered by a Motorola 6803 (don't remember the speed). Computer Devices was working on a 5 1/4" diskette based system that in addition to running Basic would also be able to run Pascal. I was the Product Support Specialist for the central US region and Canada based out of Chicago. One of the applications we were trying to sell was for insurance adjusters to be able to take the computer into the field and to be able to submit their reports directly into the system from the field. If there are any alumni reading this does anyone know what happened to John Kennedy, Garry Clark or Chip Stouffer?

Some points:
(1) Yes, that was a heatsink. The device being cooled is in a TO-220 (plastic) case.
(2) The 4000B series were CMOS IC's ranging in capacity from such as a quad two-input NOR gate to a 10-stage binary ripple counter. They ran well on anything from 3.0 volts to 15 volts DC.
(3) The ...74LSxxxx series were Schottky-clamped low-power TTL IC's, generally in the same order of complexity as the CMOS ones, but faster (and hotter). They required 5.0 +/- 0.25 volts DC to operate. Like the CMOS devices in (2), these were called "glue logic" because they interfaced the large-scale devices, such as the BIOS ROM and the CPU, itself.
(4) The mystery device in a couple of the photos was made by Fairchild Semiconductor, a company that disappeared decades ago. The legendary Bob Widlar worked for Fairchild, back in the 1960's.
You think that this technology was primitive? I started working in electronics back in the days when DTL was new. RTL was still in use back then, in the mid-1960's. A single flip-flop could take up several square inches of PC board, back in 1963.
My first job was for Hughes Aircraft, which made electronics, not aircraft. I remember designing my own digital-to-analog (and A to D) converters.

For the record, the belt driven spindle was not looking for trouble. It was very reliable! a cloth reinforced neoprene belt on a PWM brush motor, using an induction coil as the reference pulse. the old Tandon drives IBM bought for the 5150's were the same way. Though, my Ducky has a pair of direct driven drives now.. I replaced both of the stock MPI drives, an hacked the side select (which was not used on the O1. Pin 32 was a clock signal.).. the Osborne disk controller was a custom board itself. power carried to the underside of the board also led to heat breakdown of the wave-soldered board.. (yes, +5V & +12V was carried along the ribbon cable.) (some used the extra power socket on the supply, for a fan. I used a custom wired floppy power cable.)
brushless motors weren't cheap back then.. 1/2-height drives non-existant! There were a couple of companies who made custom double density boards too, which redirected the power to a cable, and added a side select to use standard Tandon drives...

LOL, back in the day, that was supposed to be one. Those little transistors (T1P110)get pretty hot in some sittuations, so depending on the load applied to it, it probably required some extra help to cool off. Pretty cool stuff. Remembrances of my youth. Cheers!

The chips from the Philippines (F6821P) are adapters for Parallel Peripheral Interfaces. Dang, it's been a while, I remember going to college and working with all those type of electronics. Cheers... Miguel Aguilar--Salt Lake City, UT. 84117. miguel@awconsultors.com

I still have my Ossie I sitting on top of my wardrobe - I actually got it to work (once) when I came to Australia in 1987. I also got a huge (3" ring binder)technical manual for it, with lots of fold-out schematics, etc. I suspect it's somewhere in the house, but I've been here for 20 years and haven't noticed it for at least a decade (black hole).

The Osborne was my FIRST! I thought I was set for life when I bought it. Two are stored in my garage - how could I part with it? Thankfully, personal porters became popular at the same time and the Osborne could be moved like luggage.

Cracking open is the right term.. I remember being refused to bring it on the plane as hand luggage and having to reluctantly place it in the hold,labelled liberally with fragile stickers much to my concern.
Standing on the bus waiting to get back to the terminal after landing I was horrified to see my beloved Osborne plummet to the ground after the luggage hatch was openned. The Osborne was about as robust as Humpty Dumpty, but then what would survive a fall from at least 4 metres.
Happy days!

This is the first computer that I did repair work. As I recalled, operation system was CP/M. Some model came with 10GB hard drive loaded with WordStar, SuperCalc, BASIC. Memory should be 64KBs. Some installed with 300 Baud rate modem. The CRT were either Amber or Green. Osborne I (1981) Specifications can be found:
http://www.computermuseum.li/Testpage/Osborne1-Specifications.htm

Awesome. Great job of dissection. I remember when, & I'm getting up there, also. I still like the old tactile mechanical keyboards. The strange black thing with wings was a heat sink. Will you look at those gigantic capacitors! My TRS-80 Model I had big ones like that, too. Notice that the RAM is soldered to the MB. Now that's OLD!

I had my company purchase an Osborne in the early 1980s as a portable computer/terminal for my work as a systems administrator. As I left the job, I purchased one myself.
A friend of mine just starting college at WPI asked "what type of computer should I buy?", and I recommended an Osborne, since his money was limited, and it provided everything he needed. Just after he bought it, Osborne announced "Chapter 11".
I felt bad for my young friend, and myself. But what I found was that a lot of Osborne products (especially software) then went on "clearance sale". I bought copies for myself, and copies for him.
He ended up with the word processor, spreadsheet, BASIC, FORTRAN, COBOL, LISP, a database engine, and several other tools. Not only did he use it, but his four roommates, and when he finished college he gave it to his younger sister.
He never regretted buying the Osborne, and neither did I.
Jon "maddog" Hall

Wow, I remember a custoner giving me two of these things around 1997, even then they were a piece of history. Boot up time, seemed like a month. They weighed as much as my car. Like a lot of independent computer shops we used to get a lot of stuff donated by well meaning customers. And, yes, some of it came in very handy at times. Could not have enough of XT boards for a few years there. And these luggables were in a class all bny themselves. Good topics and galleries guys.

The 6821 IC is a "Peripheral Interface Adaptor" (PIA)-a programmable parallel port chip originally designed by Motorola for use with the 6800 family of CPUs. BTW, the date code on the DRAM chips shows they were manufactured in 1983.

The port that you labeled the printer port was the serial port which was sometimes used as a printer port back then. The edge connector to the right of that port was the parallel printer port. I remember making many of those cables from scratch; Crimping and edge connector to a ribbon cable and then soldering the all of those wires eventually to a DB36.

The Exec had a 7"CRT, was a bit lighter, and
had lots of goodies available. The one I
still have has 512k ram, 40mb HD, DSHD drive,
internal modem, ram based quick functions,
and a very basic graphics capability. Of
course most of those items were add-ins.
Another ran my bbs (NYOUG) for a few years
with two external 5" 40mb drives that held
the entire PD software repository.
And yes, we did have at least one UG meeting
with 300 people attending...
Seriously though, one of our folks delighted
in showing us his Federal Tax SuperCalc
spreadsheets that ran on his O-1 in 29k of
memory.
I think a landmark feature of the Osborne
was its real usefulness for the normal user.
With its transition to portable format with
dual disk drives and excellent bundled
software we could be productive and
efficient.
My O-1 and later the Exec went on the
airplane with me, revising scripts and
presentations on location when few people had
anything close.

I challenge that, I happen to have owned an Osbourne one computer. It didn't have a built-in modem like that fancy one you described in your post! I had to go out and buy a 300baud external modem for my Osbourne one, and the processor speed on mine was an amazing 4 megahertz, no hard drive, and used 2 5 1/4 floppy drives. one held your program, and the other was to save your information. (example:A WordStar document). At that time I would of given my eye teeth to have the power you had.

1981 -to- 2008 and the belt is still intact. Granted this means that it was stored in a reasonablr environment, but even so, if it did break it was a $.10 fix and easy to do. Belt drive was always a great method because of the mechanical isolation. These days, in the throw away world, a belt will cost you $3-$10 if you find one. Why? Because they can.
The one big enemy of the rubber belt, or any rubber, is the modern day ozone air "cleaners". Many a fine open reel tape deck have been destroyed by these "improvers" of life.

The manual is a BIG 3-ring binder full of schematics; etc. I move to Australia in 1987 and booted the Ozzy at least one time testing using it with voltage converters. It now is collecting dust on a shelf.
I loved the software that came pre-packaged with it - one of (if not the) first computers to sell application software with the box. Got the manual for a project to time race-cars in Vancouver Canada; project fell through.

Original white case version with the cheap keyboard. Haven't powered it up in a few years. Mine has a weak power supply, and I have to use a battery to hold RTS high to use a modem.
Are there any museums in need of an Ozzie-One?
I.